1. Field of the Invention
The present invention relates generally to a continuous process for fractioning, combining, and recombining asphalt components for pelletization of asphalt and asphalt-containing products such that the pellets formed are generally uniform in dimension, freely flowing, free from agglomeration, and the pelletized asphalt is packaged, and preferably compatibly packaged, for additional processing and applications.
2. Description of the Prior Art
Pelletization equipment and its use following extrusion processing has been introduced and/or utilized in applications by the assignee for many years as is exemplified by prior art disclosures including U.S. Pat. Nos. 4,123,207; 4,251,198; 4,500,271; 4,621,996; 4,728,176; 4,888,990; 5,059,103; 5,403,176; 5,624,688; 6,332,765; 6,551,087; 6,793,473; 6,824,371; 6,925,741; 7,033,152; 7,172,397; US Patent Application Publication Nos. 20050220920, 20060165834; German Patents and Applications including DE 32 43 332, DE 37 02 841, DE 87 01 490, DE 196 42 389, DE 196 51 354, DE 296 24 638; World Patent Application Publications WO2006/087179, WO2006/081140, WO2006/087179, WO2007/064580, WO2007/089497, WO2007/142783, and WO2009/020475; and European Patents including EP 1 218 156 and EP 1 582 327. These patents and applications are all owned by the assignee and are included herein by way of reference in their entirety.
Similarly, dryer equipment has been introduced and used in applications following extrusion and pelletization for many years by the assignee as demonstrated in, for example, U.S. Pat. Nos. 3,458,045; 4,218,323; 4,447,325; 4,565,015; 4,896,435; 5,265,347; 5,638,606; 6,138,375; 6,237,244; 6,739,457; 6,807,748; 7,024,794; 7,172,397; US Patent Application Publication No. 20060130353; World Patent Application Publication Nos. WO2006/069022, WO2006/127698, WO2008/113560, WO2008/147514, and WO2009/032745; German Patents and Applications including DE 19 53 741, DE 28 19 443, DE 43 30 078, DE 93 20 744, DE 197 08 988; and European Patents including EP 1 033 545, EP 1 602 888, EP 1 647 788, EP 1 650 516. These patents and applications are all owned by the assignee and are included herein by way of reference in their entirety.
United Kingdom Patent No. GB 252,802 discloses a process by which natural asphalt including Trimidad pitch lake asphalt is dug from the source, heated directly or indirectly by steam heat to reduce it to a liquid and transferred from the stills to drums for cooling. Alternatively, this material identified as epure can be formed into block, briquettes, or pulverized for further processing and application. The heating reduces the moisture content with melting at a temperature from 300° F. to 350° F. leaving a composition for the Trimidad epure of approximately 56% bitumen and approximately 44% of earthy matter. Similarly United Kingdom Patent No. 1897 5439 discloses rinsing of the lake asphalt to remove soluble salts and non-bituminous organic matters. This rinsed asphalt is warmed by passing steam therethrough and to it is added a heavy oil as well as crushed and pulverized stone and limestone material from which combination can be made into blocks, tiles, and the like.
French Patent No. 1,519,436 discloses packaging wet granular asphalt in a bag such that the controlled amount of water present with a small amount of surfactant is sufficient to maintain the pellets in a free-flowing manner.
U.S. Pat. No. 5,688,449 discloses a method of uniformly coating an extruded plastic pellet using a binder applied to the surface of the pellet to which is adhered an additive, and more specifically to use as an additive that is an anti-blocking agent. The document remains silent regarding a uniform coating applied to asphalt and asphalt-containing pellets. In addition, the patent discloses equipment for use in batch processes wherein the pellets are placed in a rotatable drum in one portion onto which is poured the adhesive binder and subsequent additive but remains silent as to a method by which a continuous flow of pellets is uniformly coated with adhesive binder to which is continuously and uniformly applied the additive component with subsequent drying.
German Patent No. DE 44 07 822 similarly discloses a hardenable coating formed by applying a binding agent onto the damp surface of an asphalt granule or pellet and allowing the binder to dry and harden. German Patent Application Publication No. DE 195 33 011 modifies this concept by adding the binder when dry to pulverulent asphalt to form a granule or pellet that hardens on moisturization.
Mineral-coated pellets can be formed by spraying molten asphalt in a downward direction into an upward flow of air carrying fine dust particles of the minerals to be coated on the surface as disclosed in U.S. Pat. No. 3,026,568. Limestone, clay, Portland cement, mineral flour, and diatomaceous earth are cited as fine mineral powders for directly coating on the sprayed asphalt material.
Sulfur-coated pellets are disclosed in U.S. Pat. No. 4,769,288 wherein pellets are described as being rolled into shape, cooled in a controlled fashion, and subsequently dipped in molten sulfur. Use of a binder is also disclosed. The patent remains silent regarding other pelletization processes.
Geopolymers are disclosed in European Patent No. EP 0 153 097; and U.S. Pat. Nos. 4,028,454; 4,349,386; 4,472,199; 4,509,985; 4,859,367; 4,888,311; 5,288,321; 5,342,595; 5,349,118; 5,352,427; 5,539,140; and 5,798,307. These documents remain silent as to their usefulness in asphalt and asphalt composites and formulations.
A coated hot melt adhesive pellet is disclosed in U.S. Pat. No. 6,120,899 wherein the coated pellet contains from 1% to 30% of a substantially continuous non-tacky coating material. The document remains silent as to the use of such coatings on materials that are not hot melt adhesive compositions. More specifically, the instant patent does not disclose that the coating material is compatible with the remaining pellet composition on melting.
U.S. Pat. No. 4,769,288 further discloses use of extrusion to make the asphalt pellets, typically as cylinder, but remains silent as to the importance of other under-fluid pelletization processes as well as the need for controlled cooling of the extrudate to insure sufficient viscosity for the pelletization process.
Asphalt components in a compatible and meltable bag are disclosed in U.S. Pat. No. 6,358,621 wherein the polymeric bag mixes into the granules upon melting. This document remains silent as to the use of fractioning, combination, and recombination of asphalt components in pellets to prevent the coalescence of the granules on standing in the packaging.
Pavement patching including the Güssasphalt or hot mix asphalt and the Viper patch method are discussed in U.S. Pat. No. 6,362,257 wherein the former concept suffers from having poor flexibility at low temperatures and the Viper method contains large percentages of aggregate and thus is expensive to ship. A process is disclosed whereby a lightweight aggregate is combined with an air-blown asphalt binder containing additional polymers for additional structural support.
U.S. Pat. Nos. 5,513,443 and 6,164,809 disclose the use of rotating drums of various designs for drying the asphalt materials. This concept is further advanced by U.S. Pat. No. 6,440,205 wherein it is disclosed that rotating drums can be used to make pellets and coated pellets. Use of high levels of sulfur in the disclosure necessitate the control of problematic hydrogen sulfide generation which is overcome by controlled cooling of the process wherein the coolant is not in direct contact with the pelleted material as disclosed herein. These documents remain silent regarding the use of extrusion processes as well as the use of underfluid pelletization processes with asphalt. A novel horizontal mixer for use in asphalt and asphalt formulations is similarly disclosed in U.S. Pat. No. 4,140,402.
Underwater pelletization following extrusion is disclosed in U.S. Pat. No. 6,679,941 for asphalt materials. Cooling of the melt to form pellets is discussed but the document remains silent as to cooling in upstream processes. The document further discloses a continuously cooled belt typically used to produce pastilles of asphalt and the like. No disclosure of fractioning, combination, and recombination of asphalt components forming free-flowing pellets and thus to prevent agglomeration is provided in the instant patent.
World Patent Application Publication No. WO/2007/064580 discloses the use of controlled cooling processes to form asphalt pellets but remains silent as to the methods for fractioning, combining, and recombining asphalt components to form free-flowing pellets and thus to prevent undue agglomeration of the pellets as they warm toward ambient temperatures on removal from the cooling process water.
Swiss Patent CH 327640 and U.S. Pat. Nos. 4,931,231; 6,331,245; 6,357,526; and 6,361,682 disclose prilling, spraying, or sputtering concepts as a way for producing discrete pellets. U.S. Pat. No. 6,824,600 discloses formation of slates, pastilles, and pellets wherein it is stated that pellets are formed by conventional pelletizer. U.S. Pat. No. 7,101,499 discloses the use of a water jet to impact a stream of asphalt resulting in the formation of pellets. The water jet can be atmospheric or underwater as disclosed.
Compatible bagging for adhesives is disclosed in US Reissue Patent No. RE36,177 wherein the bag is melted with the contents and is applied as a component of the adhesive formulation. The components in the bag can be a single uniform mass or a collection of particles, granules, pellets, and the like. Adhesives of the natural and bitumen group as disclosed can contain asphalt, shellac, rosin and its esters but the document remains silent as to the compatible bagging of asphalt and similar asphalt-containing formulations that are not for adhesive applications.
United Kingdom Patent No. GB 2,156,392 discloses compatible polyethylene bags into which is poured previously cooled asphalt to maintain an appropriate viscosity. The bags are cooled externally by water as a bath and/or as a spray and the packaged asphalt material can be melted directly for use in applications. The patent remains silent as to extrusion processes utilizing controlled cooling as well as underwater pelletizing to form individual pellets or to the fractioning, combination, and recombination of asphalt components to form free-flowing pellets that are contained in the compatible bags. U.S. Pat. No. 3,366,233 extends this concept to multiple layer bags that are compatible with the asphalt upon melting and U.S. Pat. No. 5,254,385 discloses a similar concept such that the size of the packaging is such that it may be used as an encapsulated asphalt even suggesting the size is sufficiently small to represent a granular material.
U.S. Pat. No. 4,450,962 discloses a closable two-layer tube in which the inner layer is compatible with asphalt on melting and the outer and separate layer is readily disposable. U.S. Pat. Nos. 619,810; 4,318,475; 4,335,560; 5,878,794; and 6,003,567 disclose use of bags as liners for containing the asphalt wherein the bags in the early patents are not compatible with the asphalt and wherein the liners are not melted at the temperature at which the fluid asphalt is introduced into the bag liner. The more recent patents cited prefer the bag to be compatible when molten with the asphalt contents on application. These patents remain silent as to continuous processes including fractioning, combination, and recombination of asphalt pellets to produce free-flowing pelletized asphalt contained in compatible bags.
A process is disclosed in US Patent Application Publication No. 20060288907 for combining tacky pellets, optionally coated, with flowable fine material such that the flowable material is of sufficient quantity to maintain the separation of the tacky pellets thus avoiding agglomeration. The tacky pellets can be prepared by underwater pelletization or prilling as disclosed and can be coated with one or more layers such that the tacky pellets are rendered sufficiently non-tacky. The pellets according to at least one embodiment can be effectively distributed in the flowable fines material with vibration. The document remains silent as to the fractioning, combination, and recombination of asphalt components to form free-flowing pellets. It is further silent to the need for controlled cooling of the extrusion process prior to underwater pelletization, the necessary modifications of the equipment to facilitate the non-agglomerating transport of the asphalt pellets into and through it, and the optional use of compatible packaging material such that it can be melted with the asphalt without detrimental effect in the product applications. US Patent Application Publication No. 20080224345 further discloses the use of these packaged mixtures of pellets and flowable fines for such uses as asphalt patching, curbing, and the like.
United Kingdom Patent No. GB 2,152,941 discloses a process by which Trimidad epure is packaged with higher melting material with a particle size smaller than that of the epure such that the granulates of asphalt do not agglomerate with each other. This is particularly advantageous when the packages are stacked and compressive forces increase on the lowest bag as the stack increases. The epure is stated as being less than 25 mm and the re-cake preventing material is disclosed as being less than 2.5 mm. It is further stipulated that the material is compatible with asphalt and has a volume that is 0.5 to 2.0 times the void volume of the granulated Trimidad epure. Included with the re-cake preventing material is gilsonite, cracked asphalt pitch, ethylene-vinyl acetate copolymer, ethylene-ethyl acrylate copolymer, polyolefin, limestone powder, Portland cement, fly ash, slaked lime, kaolin, aerosil, and mixtures of two or more of these materials. Also disclosed is Trimidad Epure Z which is 12 to 13 mm Trimidad Epure combined with 8% diatomaceous earth as well as Trimidad Pulver which is a 50:50 blend of pulverulent Trimidad Epure and paving stone powder both of which were not deemed satisfactory for stable packaging.
Similarly, U.S. Pat. No. 5,728,202 discloses the combination of bitumenic materials obtained from tar sands with gilsonite to emulate the properties of Trimidad Lake Asphalt. U.S. Pat. No. 6,588,974 discloses the combination of bitumen and Fischer-Tropsch microcrystalline waxes such that upon application, the heat released by the crystallizing component assists the uniform flow of the preparation applied to road surfaces for enhanced sealing. U.S. Pat. No. 4,155,833 discloses processes whereby the microcrystalline wax content of asphaltenes is actually reduced to provide enhancement of the asphalt properties.
Canadian Patent No. 426595 discloses the combination of asphalt and preferably unsaturated organic oils to make a more elastic asphalt composition that can be combined with filler including fibrous material and subsequently can be cross-linked. Extending this concept, incorporation of rubber, including latex and recycled tires, into pulverulent asphalt such that sites of unsaturation in the rubber can be cross-linked is disclosed in United Kingdom Patent No. GB 447,416. Use of high sulfur levels, up to 7% as free sulfur or as mineral pyrites, and in association with added accelerators, in powdered Lake Asphalt or Trimidad asphalt is further disclosed for vulcanization, cross-linking, of these polymer-modified asphalts.
European Patent No. EP 0 285 865 discloses the use of bitumens and elastomers to formulate a product of specific qualities. Bitumens cited include straight-reduced asphalts, thermal asphalts, air-blown asphalts, native asphalts differentiated by mineral content, coke oven-derived tars, and residues form pyrogenous distillations. Elastomers disclosed herein include block copolymers and polymers with crystallinity. The asphalt and elastomeric components are blended together according to this disclosure to achieve the specified properties.
Use of non-volatile petroleum oils typically that are solvents for asphalts are combined with carbon blacks as disclosed in U.S. Pat. No. 3,959,006 such that the carbon black is better compatibilized with the asphalt to achieve a more uniform composition. Carbon blacks disclosed include channel black, oil furnace black, gas furnace black, detonation black, thermal plasma black, arc black, and acetylene black. This document describes the evaluation of petroleum oils or flux oils in terms of their reaction with cold fuming sulfuric acid and/or cold sulfuric acid such that first acidiffins are those that react with 85% sulfuric acid but not with cold concentrated sulfuric acid and second acidiffins are those that react with cold fuming sulfuric acid but not cold concentrated sulfuric acid. Additionally, the petroleum composition disclosed includes asphaltenes, polar compounds including nitrogen bases, and saturated hydrocarbons. Similarly, U.S. Pat. No. 7,137,305 discloses incorporation of asphalt emulsion as well as Portland cement to effect a more uniform, less porous, stabilized asphalt for use in road construction.
U.S. Pat. No. 6,927,245 discloses the use of compatibilizers to improve the interaction between the asphalt, polymer, hydrocarbon liquids, and cross-linking agents. Sulfur, sulfur-donating compounds, phenolic resins, metal oxides, as well as fatty acids and their salts are disclosed as cross-linking agents in combination with metal oxide activators and/or accelerators. The compatibilizers as disclosed can be nonpolar, polar, or a combination as necessitated by the appropriate interactions with the formulation components. Compatibility tests to determine the effectiveness of the compatibilizer for a particular formulation are further disclosed in the instant invention. This concept is further extended as disclosed in U.S. Pat. No. 6,972,047 wherein gilsonite is combined with asphalt in the presence of flux oil and various cross-linkers to improve the overall asphalt qualities and to insure compatibility of the components in the formulation thus leading to a uniform product.
U.S. Pat. Nos. 7,144,933; 7,202,290; and 7,439,286 disclose the combination of pellets containing plastomers and elastomers with pellets containing plastomer and crosslinking agent in an extrusion process with asphalt to form a cross-linkable asphalt formulation. According to the disclosure the plastomer is preferably an oxidized polyolefin, a maleated polyolefin, or an acrylic acid grafted polyolefin. Elastomers are generically described as any synthetic rubber compound. The cross-linking agent can be one of elemental sulfur, hydrocarbyl polysulfides, peroxides, and transition metals. Crosslinking accelerators are also disclosed. The patents remain silent as to the method of pelletization for the plastomer/elastomers pellets as well as the plastomer/cross-linker pellet. They are also silent as to the pelletization of the asphalt formulation on extrusion. Similar processes are disclosed in U.S. Pat. No. 6,569,925 wherein the sulfur and other accelerators and modifiers are prepared in a gel to provide further stabilization prior to introduction into the asphalt preparation.
Similarly, U.S. Pat. No. 7,303,623 discloses the pelletization of sulfur or lime in combination with asphalt-compatible binders for use in asphalt formulations. The pelletization process is generically disclosed to include an extruder, die head and die opening. It is stated that the pellet formed can be either too moist or too hot for cutting and drying and/or cooling as disclosed prior to pelletization. The patent remains silent as to the concept of pelletization under fluid immediately at the cutter head as well as to the fractioning, combination, and recombination of asphalt components to form free-flowing pellets for packaging.
Chemically modified asphalt is disclosed in U.S. Pat. No. 5,306,750 wherein asphalt is chemically linked to epoxides for enhancement of the asphalt performance. Modifications of polyoxyalkylenes to contain functional groups reactive with asphalts to effect cross-linking are disclosed in U.S. Pat. No. 7,452,930.
United Kingdom Patent No. GB 483,907 combines asphalt with natural and synthetic rubbers, latex, as well as vegetable oils, animal fats and oils, as well as fatty acids to improve the elasticity of bitumens. Use of various sulfur-containing compounds is further disclosed such that heating the asphalt or the asphalt-rubber-and/or-oil blends resulted in oxidation and addition products of the formulation leading to enhancement of properties as well as reduction of water and residual sulfur content. The sulfur compounds herein disclosed include sulfuric acid, fuming sulfuric acid, sulfur trioxide, pyrosulfuric acid, polythionic acids, persulfuric acid, sulfur sesquioxide, and sulfur heptoxide. This document also discloses bitumenic sources including asphaltic, pitch, and tar derivatives of asphalts, mineral oils, lignite-tars, coal-tars, peat-tars, shale oil, wood-tar, resin-tar, fat-tar, and bone-tars, as well as montan pitch, and residues from distillation, refining, hydrogenation, and cracking process for petroleum. Similar processes are disclosed in U.S. Pat. No. 6,228,909 wherein additional mineral acids are utilized to enhance the oxidation of the asphalt in various formulary processes.
U.S. Pat. No. 4,437,896 discloses a synthetic asphalt made with combination of gilsonite or synthetic gilsonite, also known as soft coal or flaked asphaltene residuum, to replace the asphaltene portion of asphalt and tall oils and/or tall oil pitches obtained from the destructive distillation of pine and poplar trees to replace the maltenes portion of asphalt. Modifications of natural gilsonite or uintaite are disclosed in U.S. Pat. No. 5,047,143 such that nonpolar saturated hydrocarbons are combined with uintaite to extract lower melting components essentially to form a maltene-like component. This then can be combined with the residuum from the extraction process, essentially an asphaltene, to form a synthetic asphalt.
U.S. Pat. No. 4,494,958 combines pulverulent asphaltites or oil-bearing coal, solidified petroleum composed of 25% to 75% fixed carbon resulting from the slow and progressive loss of volatiles, such as grahamite with powdered bituminous materials such as lignite. Though similar, asphaltites are differentiated from coal by their ability to be dissolved in carbon disulfide. The instant patent remains silent as to the use of these combinations as filler in asphalts or asphalt formulations or as anti-blocking agents for enhancement of the product properties. U.S. Pat. No. 3,902,914 discloses the use of oil shale fines, regular shale fines, diatomaceous earth, rhyolite fines, slate fines, in lieu of or in combination with more conventional fillers including limestone dust, asbestos, silica, flour, clay, and Portland cement. These novel filler materials in combination with asphalts used to produce asphalt cement, as disclosed, exhibit better aging and adhesion properties than with conventional materials.
U.S. Pat. No. 4,227,933 discloses the use of finely-divided particulate Trimidad Lake asphalt in combination with fine aggregate to make an essentially void-free pavement surfacing material. Use of asphalt to coat aggregate with very thin films is disclosed in U.S. Pat. No. 1,343,680 whereby foaming was found to achieve a more uniformly thin layer. These coated aggregates were used to form excellent asphalt cement as disclosed.
Mastic asphalt is disclosed in United Kingdom Patent No. GB 697,327 as a combination of finely graded mineral matter together with asphaltic cement to form a solid or semi-solid coherent mass free of voids and sufficiently fluid to be spread by means of a hand float. Asphaltic cement is disclosed herein as asphaltic bitumen, lake and natural asphalt, asphaltic resins, coal tar resins or pitches, and pitches that result from low-temperature carbonization, as well as refined natural and synthetic vegetable resins. Flux oil and combinations of these are materials are disclosed. The finely graded mineral matter is further disclosed as being any powder that does not react with asphaltic cement including limestone or siliceous powder, grit, chippings, exfoliated minerals, vermiculite, as well as fibrous materials including asbestos and wood.
U.S. Pat. No. 7,025,822 similarly discloses mastic preparations utilizing waste solids obtained from sludges including separator sludges, sludges from air flotation systems, slop oil emulsion sludges, tank bottoms, sludges from heat exchange bundles, sediment from crude oil storage tanks, clarified slurry oil tank sediments, and sludges from in-line filters, and sludges from drainage ditches in combination with asphalt materials. Incorporation of polymers and recycled asphalt pavement or “RAP” is also disclosed.
United Kingdom Patent No. GB 167,344 discloses the use of roofing felt that has completely been broken into separate fibers in combination with asphalt wherein mixing is done on the 3% to 4% dried fiber in the asphalt at a temperature between 300 and 450° F. such that the fibers are uniformly dispersed. Use of cellulosic fibers in the presence of organic bases to form asphaltic compositions that are more stable to temperature degradation is disclosed in U.S. Pat. No. 6,562,118. Such compositions are identified as fiber modified asphalt or “FMA”.
U.S. Pat. No. 5,028,266 similarly discloses incorporation of fibers into bitumen. This is done by contacting the fibers in a volatile or soluble binder and incorporating this into a liquid bitumen. This formulation is then added to the bitumen such that with heat or solution the binder is removed and the fiber is uniformly and homogeneously distributed throughout the bitumen preparation.
South African Patent No. ZA 99/1678 and U.S. Pat. No. 6,558,462 disclose a stabilizer that when mixed with pelletized or powdered Trimidad Lake asphalt or polymer modified Trimidad Lake asphalt prevents coalescing of the discrete particles during storage or transport. It is further disclosed that the stabilized product can be stored in bags with which the asphalt is compatible such that the entire bag and contents can be added into the mixing process such as for road building materials. Among the stabilizers are included preferentially are clay, carbonaceous materials, silica, polymers, natural or synthetic fibers, carbon black, and charcoal. Generically the stabilizer can be any material that increases the melting point, increases the surface tension, and/or increases the softening point of the Trimidad Lake asphalt.
Separation of natural asphalt and particularly Trimidad asphalt into two or more fractions to facilitate ease of handling and transport is disclosed in United Kingdom Patent No. GB 274,540. Separation is achieved after reduction of the water content by addition of a light solvent oil such that further heat melts and dissolves the bitumen portion of the composition or approximately 55%. The bitumen solution is removed from the powdery residue and the bitumen portion can be recovered by reduction of the light solvent oil without alteration of the properties of the fractions. It is further disclosed that the separate components can be recombined without alteration of the original properties.
Solvent deasphalting is a commonly used technique to separate the undesired asphaltenes from other asphalt components in petroleum distillation processes. Conversely, the patent remains silent to solvent deasphalting that can be used to remove undesired more soluble components from the desired asphaltenes important to the asphalt industry. Various techniques, solvents and solvent combinations and their benefits are disclosed in U.S. Pat. No. 3,018,228 (extractive distillation with ethylene carbonate); U.S. Pat. No. 4,452,691 (oxygenated solvents including alcohols and hetero- and halo-modified analogs of oxygenated solvents); U.S. Pat. Nos. 4,618,413 and 4,643,821 (carbonates, thiocarbonates, and dimethyl sulfone); U.S. Pat. No. 5,346,615 (alkyl and cyclic carbonates); and U.S. Pat. No. 6,533,925 wherein the conventional solvent process is disclosed including the common solvents such as methane, ethane, propane, butane, isobutane, pentane, isopentane, neopentane, hexane, isohexane, heptane, and mono-olefinic equivalents. The process as disclosed optimizes the asphaltene separation, solvent conversion, in combination with gasification processes. U.S. Pat. No. 2,726,192 discloses the use of n-butanol, preferably in counter-current extraction to further purify the asphalt following propane solvent-deasphalting processes.
In contrast to United Kingdom Patent No. GB 252,802 hereinabove described, United Kingdom Patent No. GB 299,208 discloses the use of epure described as “natural Trimidad asphalt freed from earthy impurities”. This epure is further disclosed to be elastic with a melting point between 150° and 160° C. (approximately 302° to 320° F.) but is brittle due to a high ash content. This epure is then combined with goudron, identified as a fatty asphalt with a melting point between 90° and 100° C. obtained as a distillation product mainly from Trimidad asphalt, and pitch. Asbestos fiber is added as well to confer enhanced toughness or hardness to the formulated material.
A waterproofing formulation is disclosed in United Kingdom Patent No. 320,886 in which a Trimidad type asphalt is initially heated to approximately 400° F. for approximately 18 hours to remove a relatively small amount of light naphtha by distillation. To this is added gilsonite material that has separately and similarly been heated at approximately 680° F. to remove light naphtha such that the final combination on cooling is free of lighter naphthas that are identified as detrimental to the solvent-based preparation of the invention.
United Kingdom Patent No. GB 714,091 discloses refining processes for Trimidad Lake asphalt such that the courser silica content is removed from the mineral fraction while leaving the colloidal clay component in combination with the bitumenic components. Course organic matter is removed from the melt and only silica greater than 10 microns is selectively removed as disclosed herein. The process prevents the undesirable agglomeration of the clay particles in association with organics to form lumps that prior art processes unfortunately removed. Hydraulic separation and classification is the preferred process of the instant invention. U.S. Pat. No. 2,594,929 similarly discloses the use of hydraulic separation to remove the coarse siliceous materials from the Trimidad Lake asphalt.
U.S. Pat. No. 1,948,296 discloses the preparation of asphalt from an oil containing asphalt whereby the oil is dissolved in a solvent allowing separation of the asphalt. The asphalt is then recombined with a different oil and subjected to oxidation to form a higher quality product. Propane is preferentially used to extract the petroleum oil leaving the desired asphalt residue. This asphalt residue is isolated and recombined with a fluxing oil including gas oil, light lubricating distillate, ordinary distillate, fuel oil, liquid asphalt, and road oil with heating to melt and uniformly mix the components. Oxidation is achieved by passing through the melt at elevated temperature.
Similarly, U.S. Pat. No. 2,503,175 discloses the use of petroleum-derived solvents including mineral spirits, heating oil, coal tar distillates, and solvent naphtha as well as chlorinated solvents and carbon disulfide to extract the bitumenic portion and colloidal clay allowing the sand, particularly the coarser sand components, to be removed from Trimidad asphalt. Use of water or aqueous solutions is also disclosed to facilitate the separation process.
Solvent extraction of liquid petroleum from asphalt is also disclosed in U.S. Pat. No. 2,081,473. Processes utilizing liquid sulfur dioxide to separate paraffinoid and non-paraffinoid oils are also disclosed. Polar solvent such as aniline, methyl formate, and acetone in combination with benzol are disclosed as less effective in achieving the separation.
U.S. Pat. No. 3,779,902 discloses the use of variable composition solvents to selectively extract portions from an asphaltic material such as Athabasca bitumen. Single solvents and solvent mixtures as disclosed include paraffinic or isomeric hydrocarbons, saturated substituted cycloparaffins, as well as saturated unsubstituted cycloparaffins. The solvent power of the aliphatic solvents is disclosed in comparison to that of aromatic solvents. By choice of solvents and solvent combinations, selective precipitation of asphaltenes ranging from 0% to 100% can be achieved.
The benefit of combining refined Trimidad Asphalt and refinery or petroleum asphalt to form improved more ductile asphalt concrete pavements is disclosed in U.S. Pat. No. 4,274,882. Benefit is disclosed in U.S. Pat. No. 4,428,824 whereby asphalt components are separated to yield the asphaltene material and a deasphalted oil. The oil is visbroken and subsequently recombined with the asphaltene to produce a product of lower viscosity and lower pour point. This is utilized in formulations typically requiring volumes of cutter stock such that the product disclosed significantly reduces that volume to yield a formulation of at least comparable results. Other conversion and reformulation techniques are disclosed in U.S. Pat. No. 4,514,283 wherein asphaltenes are precipitated from viscous crude oils such that the asphaltenes can be mildly thermalized, and upon recombination with the residual crude oil forms a less viscous more pumpable oil product.
Similarly U.S. Pat. Nos. 2,783,188 and 2,940,920 disclose use of paraffin and olefinic solvents in various combinations to separate the insoluble asphaltenes from the solvent-soluble portion identified as petrolenes. This document clearly discloses that separation occurs to form two immiscible or only very slightly miscible liquid phases at elevated temperature. U.S. Pat. No. 3,278,415 discloses two-phase separations in which one phase is an aliphatic solvent as above and the second phase is an aqueous phenolic solution. U.S. Pat. No. 4,211,633 discloses the use of natural gasoline fractions to effect separation such that the asphalt produced contains less heptane-soluble material.
Aqueous emulsions of asphalt are improved by addition of Trimidad asphalt, Bermudez asphalt, and montan wax as disclosed in United Kingdom Patent No. 332,591. Use of these enhanced emulsions was found to reduce decomposition on contact with porous bodies such as road stones used in paving. The enhancement is attributed to high molecular weight organic acids, identified as asphaltogens, present in these materials. United Kingdom Patent No. 462,111 extends these concepts by disclosing the use of tar pitches, oil pitches, pitches from destructive distillation of animal and vegetable matter, as well as pitches from destructive distillation of native bitumens and includes asphalts, asphaltites, coal, peat, and lignite. Asphaltites are further disclosed as gilsonite, grahamite, and glance pitch and any of these materials can be combined with any of the other materials regardless of hardness to achieve an appropriate final product emulsion. U.S. Pat. Nos. 4,073,659; 4,094,696; 4,193,815; and 4,621,108 disclose the formation of aqueous emulsions comprised of asphalt and/or gilsonite wherein some solvent can be used to better facilitate the stability of the emulsion formed.
U.S. Pat. Nos. 3,978,925; 3,983,939; and 3,993,555 discloses solvent extraction and thermal processes for recovery of oil and bitumen from tar sands. Viscous oil recovery from formations is facilitated by use of steam injections in combination with various amines as disclosed in U.S. Pat. No. 4,156,463. Comparison of effects from combinations of steam with polar solvents, nonpolar solvents, aromatic solvents, and carbon dioxide are also provided.
Asphaltenes often are problematic in wells, pipeline transport, and drilling operations and U.S. Pat. No. 5,504,063 discloses the use of alkyleneamine-fatty acid condensation reaction products in combination with polar aprotic high dielectric constant solvents to remove and inhibit such deposits. Use of acetone in combination with paraffinic, olefinic, naphthenic, and aromatic solvents for similar removal of asphaltenic deposits is disclosed in U.S. Pat. No. 2,970,958. Aliphatic ketones in combination with aromatic solvents are preferably disclosed. Similarly, the use of aromatic hydrocarbons with amines is disclosed in U.S. Pat. No. 3,914,132 and U.S. Pat. No. 4,379,490 discloses the use of amine-activated aliphatic disulfide oils to effect solution of deleterious asphaltenes.
U.S. Pat. No. 2,766,132 discloses the incorporation of polyaminoimidazolines into bituminous mixtures to enhance the wetting of the various aggregates with the bitumenic preparation. This enhancement reduces the proclivity of the aggregates, and especially carbonates, to slow leaching of the mineral content with the subsequent separation or stripping of the bitumen from the surface of the aggregate materials.
What is needed then is a process, preferably a continuous process, to form free-flowing pellets that can be packaged for further processing or use in asphalt and asphalt-containing applications such that the asphalt source materials used can be fractioned into a multiplicity of asphalt components that can be at least partially recombined as well as combined with other asphalt and modifier components that on pelletization produce those freely flowing pellets that are not subject to cold flow and are resistant to compression on packaging and storage.